// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_COMPRESSION_ATTRIBUTES_POINTS_SEQUENCER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_POINTS_SEQUENCER_H_

#include <vector>

#include "draco/attributes/point_attribute.h"

namespace draco {

// Class for generating a sequence of point ids that can be used to encode
// or decode attribute values in a specific order.
// See sequential_attribute_encoders/decoders_controller.h for more details.
class PointsSequencer {
  public:
    PointsSequencer() : out_point_ids_(nullptr) {}
    virtual ~PointsSequencer() = default;

    // Fills the |out_point_ids| with the generated sequence of point ids.
    bool GenerateSequence(std::vector<PointIndex> *out_point_ids) {
        out_point_ids_ = out_point_ids;
        return GenerateSequenceInternal();
    }

    // Appends a point to the sequence.
    void AddPointId(PointIndex point_id) {
        out_point_ids_->push_back(point_id);
    }

    // Sets the correct mapping between point ids and value ids. I.e., the inverse
    // of the |out_point_ids|. In general, |out_point_ids_| does not contain
    // sufficient information to compute the inverse map, because not all point
    // ids are necessarily contained within the map.
    // Must be implemented for sequencers that are used by attribute decoders.
    virtual bool UpdatePointToAttributeIndexMapping(PointAttribute * /* attr */) {
        return false;
    }

  protected:
    // Method that needs to be implemented by the derived classes. The
    // implementation is responsible for filling |out_point_ids_| with the valid
    // sequence of point ids.
    virtual bool GenerateSequenceInternal() = 0;
    std::vector<PointIndex> *out_point_ids() const {
        return out_point_ids_;
    }

  private:
    std::vector<PointIndex> *out_point_ids_;
};

}  // namespace draco

#endif  // DRACO_COMPRESSION_ATTRIBUTES_POINTS_SEQUENCER_H_
